This invention relates to a cooling flow path used for the thrust bearing of an air cycle machine.
One type of air cycle machine uses a radial outflow compressor that is driven by two radial turbines. The compressor and turbines are supported on a common shaft and ride upon hydrodynamic bearings in a housing. A pair of hydrodynamic, foil-type journal bearings support the shaft. The shaft includes a thrust runner. Axial forces imparted on the shaft are counteracted by a pair of thin foil hydrodynamic thrust bearings arranged on either side of the thrust runner.
Various seals are used in the housing to separate the flow into and out of the compressor and turbines seals also help define a cooling path in the housing. Airflow through the cooling path cools the hydrodynamic bearings. One problem has been that hot air from the compressor outlet can leak past a seal between the compressor rotor and housing. The leaked hot compressor air has then flowed through the hydrodynamic thrust bearings, which can reduce their life.
What is needed is an improved cooling path to address leakage from the compressor and route the leakage around the hydrodynamic thrust bearings.